134 lines
2.8 KiB
Go
134 lines
2.8 KiB
Go
package collector
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import (
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"encoding/json"
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"fmt"
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"io/ioutil"
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"net/http"
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"net/url"
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"strconv"
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"time"
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"github.com/oliveagle/jsonpath"
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corev1 "k8s.io/api/core/v1"
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)
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// JSONPathMetricsGetter is a metrics getter which looks up pod metrics by
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// querying the pods metrics endpoint and lookup the metric value as defined by
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// the json path query.
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type JSONPathMetricsGetter struct {
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jsonPath *jsonpath.Compiled
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scheme string
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path string
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port int
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}
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// NewJSONPathMetricsGetter initializes a new JSONPathMetricsGetter.
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func NewJSONPathMetricsGetter(config map[string]string) (*JSONPathMetricsGetter, error) {
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getter := &JSONPathMetricsGetter{}
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if v, ok := config["json-key"]; ok {
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pat, err := jsonpath.Compile(v)
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if err != nil {
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return nil, fmt.Errorf("failed to parse json path definition: %v", err)
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}
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getter.jsonPath = pat
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}
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if v, ok := config["scheme"]; ok {
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getter.scheme = v
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}
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if v, ok := config["path"]; ok {
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getter.path = v
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}
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if v, ok := config["port"]; ok {
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n, err := strconv.Atoi(v)
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if err != nil {
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return nil, err
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}
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getter.port = n
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}
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return getter, nil
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}
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// GetMetric gets metric from pod by fetching json metrics from the pods metric
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// endpoint and extracting the desired value using the specified json path
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// query.
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func (g *JSONPathMetricsGetter) GetMetric(pod *corev1.Pod) (float64, error) {
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data, err := getPodMetrics(pod, g.scheme, g.path, g.port)
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if err != nil {
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return 0, err
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}
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// parse data
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var jsonData interface{}
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err = json.Unmarshal(data, &jsonData)
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if err != nil {
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return 0, err
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}
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res, err := g.jsonPath.Lookup(jsonData)
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if err != nil {
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return 0, err
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}
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switch res := res.(type) {
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case int:
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return float64(res), nil
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case float32:
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return float64(res), nil
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case float64:
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return res, nil
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default:
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return 0, fmt.Errorf("unsupported type %T", res)
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}
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}
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// getPodMetrics returns the content of the pods metrics endpoint.
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func getPodMetrics(pod *corev1.Pod, scheme, path string, port int) ([]byte, error) {
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if pod.Status.PodIP == "" {
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return nil, fmt.Errorf("pod %s/%s does not have a pod IP", pod.Namespace, pod.Namespace)
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}
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httpClient := &http.Client{
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Timeout: 15 * time.Second,
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Transport: &http.Transport{},
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}
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if scheme == "" {
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scheme = "http"
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}
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metricsURL := url.URL{
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Scheme: scheme,
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Host: fmt.Sprintf("%s:%d", pod.Status.PodIP, port),
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Path: path,
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}
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request, err := http.NewRequest(http.MethodGet, metricsURL.String(), nil)
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if err != nil {
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return nil, err
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}
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resp, err := httpClient.Do(request)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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data, err := ioutil.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("unsuccessful response: %s", resp.Status)
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}
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return data, nil
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}
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